However, when his prothrombin activity was investigated on admission for an episode of pulmonary haemorrhage, his coagulation profile was as follows: INR of 1.8, a PT of 25.3 s (normal range 9–13), activated partial thromboplastin time (aPTT) of 56 s (normal range 25–37), factor II level of 53% (normal range 70%–130%, consistent with warfarin effect), a dilute Russell's viper venom time ratio of 1.79, lupus aPTT ratio of 2.10 (lupus anticoagulant positive), factor VIII level of 254% (normal range 70–220) and factor XI of 123% (normal range 55–130). Here, F2 is linked to systemic lupus erythematosus.